High-frequency ultrasound imaging can be performed with greater quality and suppressed grating lobes by using methods and systems for effectively reducing the temporal length of transmit grating lobe signals in received ultrasound echoes. Systems and methods are provided for improved high-frequency ultrasound imaging. In various aspects, the method of shortening the time domain of grating lobe signals comprises splitting an array of N transmit elements into K sub-apertures. In further aspects, the grating lobes are suppressed by performing signal processing of the shortened grating lobe signals. In certain aspects, the signal processing method comprises weighting the samples by a calculated phase coherence factor.
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1. A method of performing ultrasound imaging, comprising: transmitting a defocused pulse from an array of ultrasound elements, the defocused pulse having a virtual point source behind the array of ultrasound elements; receiving broadband reflections with the array of ultrasound elements, and obtaining signals from the reflections; applying receive beamforming delays to the signals and calculating phase coherence weighting factors along different A-scan lines, thereby obtaining a spatial map of phase coherence weighting factors; transmitting beamformed pulses from the array of ultrasound elements along one or more A-scan lines; and applying the spatial map of phase coherence weighting factors when performing receive beamforming on the signals to reduce grating lobes in an ultrasound image.
Ultrasound imaging is performed by first transmitting a defocused pulse from an array of ultrasound elements, creating a virtual point source behind the array. Broadband reflections are received, generating signals. Receive beamforming delays are applied to these signals, and phase coherence weighting factors are calculated along different A-scan lines, resulting in a spatial map of these factors. Beamformed pulses are then transmitted from the array along A-scan lines. Finally, the spatial map of phase coherence weighting factors is applied during receive beamforming to the signals, which reduces grating lobes in the final ultrasound image, improving image quality.
2. The method according to claim 1 wherein the phase coherence weighing factors are sign coherence factors.
The ultrasound imaging method, which involves transmitting a defocused pulse from an array of ultrasound elements, creating a virtual point source behind the array, receiving broadband reflections and obtaining signals, applying receive beamforming delays and calculating phase coherence weighting factors to obtain a spatial map, transmitting beamformed pulses, and applying the spatial map to reduce grating lobes, refines the phase coherence weighting factors. Specifically, the phase coherence weighting factors used are sign coherence factors.
3. The method according to claim 1 wherein the array of ultrasound elements has an element-to-element pitch greater than 0.5*lambda, wherein lambda is the wavelength of the beamformed pulses.
The ultrasound imaging method, which involves transmitting a defocused pulse from an array of ultrasound elements, creating a virtual point source behind the array, receiving broadband reflections and obtaining signals, applying receive beamforming delays and calculating phase coherence weighting factors to obtain a spatial map, transmitting beamformed pulses, and applying the spatial map to reduce grating lobes, uses a specific array configuration. The element-to-element pitch of the ultrasound element array is greater than 0.5 times lambda (0.5*lambda), where lambda represents the wavelength of the transmitted beamformed pulses.
4. An ultrasound imaging system comprising: an ultrasound imaging array comprising an array of ultrasound elements; a transmit beamformer operatively coupled to the ultrasound imaging array, wherein said transmit beamformer is configured to apply energy selectively to the ultrasound elements; a receive beamformer operatively coupled to the ultrasound imaging array, wherein said receive beamformer is configured to sample a signal received by said ultrasound imaging array at each of the ultrasound elements; and processing circuitry operatively connected to said transmit beamformer and said receive beamformer, wherein said processing circuitry is configured to: control said transmit beamformer such that a defocused pulse is transmitted from said ultrasound imaging array, the pulse having a virtual point source behind said ultrasound imaging array; receive, from said receive beamformer, signals produced from broadband reflections; apply receive beamforming delays to the signals and calculating phase coherence weighting factors along different A-scan lines, thereby obtaining a spatial map of phase coherence weighting factors; transmit beamformed pulses from the ultrasound imaging array along one or more A-scan lines; and apply the spatial map of phase coherence weighting factors when performing receive beamforming on the signals to reduce grating lobes in an ultrasound image.
An ultrasound imaging system includes an ultrasound imaging array comprising ultrasound elements. A transmit beamformer, coupled to the array, applies energy to the elements. A receive beamformer, also coupled to the array, samples the signal received by each element. Processing circuitry controls both beamformers. The circuitry controls the transmit beamformer to transmit a defocused pulse from the array, creating a virtual point source behind the array. It receives signals from broadband reflections via the receive beamformer. It then applies receive beamforming delays to the signals and calculates phase coherence weighting factors along different A-scan lines to get a spatial map. Beamformed pulses are transmitted, and the spatial map is used during receive beamforming to reduce grating lobes, improving the ultrasound image.
5. The system according to claim 4 wherein the phase coherence weighing factors are sign coherence factors.
The ultrasound imaging system, which contains an ultrasound imaging array, a transmit beamformer, a receive beamformer, and processing circuitry to transmit defocused pulses, calculate phase coherence weighting factors to obtain a spatial map, transmit beamformed pulses, and apply the spatial map to reduce grating lobes, specifies the type of phase coherence weighting factors used. The phase coherence weighting factors are sign coherence factors.
6. The system according to claim 4 wherein said ultrasound imaging array has an element-to-element pitch greater than 0.5*lambda, wherein lambda is the wavelength of the beamformed pulses.
The ultrasound imaging system, which contains an ultrasound imaging array, a transmit beamformer, a receive beamformer, and processing circuitry to transmit defocused pulses, calculate phase coherence weighting factors to obtain a spatial map, transmit beamformed pulses, and apply the spatial map to reduce grating lobes, uses a specific array configuration. The element-to-element pitch of the ultrasound array is greater than 0.5*lambda, where lambda is the wavelength of the beamformed pulses.
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May 14, 2015
August 15, 2017
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